Electricity Generation

Waste-to-Energy

In a sustainable world, waste would be reduced from the outset and composted, recycled, or reused. The current reality, however, is that cities and land-scarce countries face a dilemma about what to do with their trash. Waste-to-energy is a transitional strategy for a world that wastes too much and needs to reduce its emissions.

Incineration, gasification, and pyrolysis are means of releasing the energy contained in trash. Some of the heavy metals and toxic compounds latent within it are emitted into the air, some are scrubbed out, and some remain in residual ash. With these outcomes, why bother at all? Waste-to-energy plants create energy that might otherwise be sourced from coal- or gas-fired power plants. Their impact on greenhouse gases is positive when compared to landfills that produce methane emissions as organic wastes decompose.

At Project Drawdown, we consider waste-to-energy a regrets solution. It has a positive impact on emissions, but social and environmental costs are harmful and high. It can help move us away from fossil fuels in the near-term, but is not part of a clean energy future. Even when incineration facilities are state-of-the-art (and many are not), they are not truly clean and toxin-free.

#68

Rank and Results by 2050

1.1 gigatonsreduced CO2

$36 Billionnet implementation cost

$19.82 Billionnet operational savings

Impact: The risks of waste-to-energy are significant, but it has some benefits: 1.1 gigatons of carbon dioxide emissions can be avoided by 2050, primarily due to reduced methane emissions from keeping waste out of landfills. Considering the disadvantages, this is a “bridge” solution — one that will decline as preferable waste-management solutions, including zero waste, composting, and recycling, become more widely adopted globally. Island nations, with limited available space, may continue to use waste-to-energy as an alternative to landfilling—employing more advanced technologies, such as plasma gasification, to limit the negative impacts. At a $36 billion cost to implement, savings over thirty years could be $20 billion.

Technical Summary

Waste-to-Energy

Project Drawdown defines waste-to-energy as: the combustion of waste and conversion to electricity and usable heat in waste-to-energy plants. This solution replaces conventional electricity-generating technologies such as coal, oil, and natural gas power plants.

Waste-to-energy reduces greenhouse gas emissions in many cases, though the magnitude of that reduction varies substantially depending on the baseline used for comparison. Key considerations in waste-to-energy’s case include: the caloric content of combusted waste; its methane generation potential (were it to be landfilled); likely alternative waste disposal pathways; and the emissions intensity of electricity and/or heat being displaced by that generated by the waste-to-energy process.

Waste-to-energy has seen wide adoption in Europe, the USA, and Japan, and adoption is growing rapidly in China. The Organisation for Economic Co-operation and Development (OECD) countries are most likely to see significant growth in its market penetration moving forward, as the primary barriers to entry for waste-to-energy are high capital cost (in part due to high-cost pollution control technologies, which are essential in mitigating potential adverse public health impacts) and the reliable availability of municipal solid waste with a high caloric heating value. Waste-to-energy adoption will have the largest climate impact when it displaces both landfill disposal (particularly with low methane capture) and carbon-intensive power generation, i.e. coal, natural gas, and oil combustion.

Methodology

Waste-to-energy adoption is presented in two ways: in terawatt-hours of electricity generation, and in tons of waste produced. Both types of presentations are used in our adoption prognostications.

The total addressable market for waste-to-energy is based on projected global electricity generation from 2020-2050. Current adoption [2] was estimated at 0.39 percent of generation (87.7 terawatt-hours). Adoption data from the Intergovernmental Panel on Climate Change (IPCC, 2007), The World Bank (1999), IRENA (2016), the IEA (2016), and Greenpeace (2015) are used to project current and future adoption.

Impacts of increased adoption of waste-to-energy from 2020-2050 were generated based on three growth scenarios, which were assessed in comparison to a Reference Scenario where the solution’s market share was fixed at the current levels

Plausible Scenario: This scenario is built upon a reference case scenario generated from custom calculations based on the available literature. In this reference case scenario, prognostications are created from the bottom up, on a country-by-country level. Waste-to-energy is projected to increase by 7.5 percent each year for countries where it is already present. New penetration into the market occurs in 2020 for OECD countries with zero waste-to-energy systems at present, and in 2030 for all other countries, at an initial rate of 1 percent adoption. Tons of waste used in waste-to-energy processes are converted to terawatt-hours of electricity produced by multiplying by an estimated heating value of waste and average efficiency of waste-to-energy plants.

Drawdown Scenario: This scenario has an adoption trajectory driven based on the feedstock from the output of the Project Drawdown Waste Integration Model. This results in a 0.44 percent share of the total electricity generation portfolio in 2050.

Optimum Scenario: This scenario also has an adoption trajectory driven based on the feedstock from the output of the Project Drawdown Waste Integration Model. This results in a 0.33 percent share of the total electricity generation portfolio in 2050.

The uncertainty associated with the future adoption of waste-to-energy is linked to other waste management solutions: landfill methane capture, methane digesters, recycling, and composting could affect the balance of available waste for each solution. Thus, the Drawdown and Optimum Scenarios have lower adoption trajectories of waste-to-energy than the Plausible Scenario.

Emissions Model

The result of the assessment is a regionally explicit forecast of waste-to-energy adoption and climate impacts, in terms of both avoided methane and carbon dioxide emissions. Landfill methane emission rates are estimated using the first-order decay method recommended by the IPCC in order to estimate total emissions reduction for waste-to-energy in comparison with sending the waste to a landfill.

Financial Model

The financial inputs used in the model assume an average installation cost of US$3,539 per kilowatt. [4] Since waste-to-energy using incineration is a mature technology that has been in widespread use in OECD countries for many decades, a learning rate of 2 percent is applied to first costs. An average capacity factor of 52 percent is used for waste-to-energy plants from historical data, compared to 55 percent for conventional technologies.

Results

The results for the Plausible Scenario show that through advanced global adoption of waste-to-energy from 2020-2050, 62.6 gigawatts of waste-to-energy plants can be installed globally, increasing the electricity generation market share for this technology from 0.39 percent to 0.55 percent. This will result in the avoided emissions of 1.1 gigatons of carbon dioxide-equivalent greenhouse gases. The net cost compared to the Reference Scenario would be US$36 billion from 2020-50, and around US$19.82 billion in net savings for waste-to-energy plants over the same period.

Despite the integration with other waste management solutions covered in Project Drawdown, the climate impacts of the Drawdown and Optimum Scenarios are similar to the Plausible Scenario, with emission reductions over 2020-2050 of 0.9 and 1.23 gigatons carbon dioxide-equivalent, respectively.

Discussion

While preferable to landfilling, waste-to-energy is seen as a “regrets” solution, which is best served as a bridge technology before other preferable waste management options become fully possible.

Promotion of waste-to-energy will be most successful where waste disposal and electricity costs are high, and where capital is readily available. Waste-to-energy should be promoted appropriately in each region’s context, within a broader framework of integrated solid waste management. This is all the more important given the potentially significant public health risk that insufficiently regulated waste-to-energy can pose (and has historically posed) to nearby communities. When appropriately strict pollution controls are in place, and when landfilling is a likely waste disposal alternative, waste-to-energy will nonetheless continue to provide an opportunity for societally beneficial greenhouse gas emissions reduction.

New waste-to-energy research in Europe and the USA is relatively sparse now, as a result of the technology’s maturity. More active research is ongoing, particularly in East Asia. In general, research resources are more heavily allocated to new technologies such as gasification, pyrolysis, and plasma-arc gasification (as opposed to combustion). While these technologies are common in Japan, they have yet to become mainstream in any other part of the world.

[1] For more about the Total Addressable Market for the Energy Sector, click the Sector Summary: Energy link below.

[2] Current adoption is defined as the amount of functional demand supplied by the solution in the base year of study. This study uses 2014 as the base year due to the availability of global adoption data for all Project Drawdown solutions evaluated.